Television apparatus and method



Oct. 17, 1939. A. GOULD TELEVISION APPARATUS AND METHOD 3 Sheets-Sheet 1Filed Jan. 23, 19:52

6am 05cm umoR ZesZZeA. Goald I ENTOR.

ORNEY Oct. 17, 1939. L. A. GOULD 2,176,856

TELEVISION APPARATUS AND METHOD Filed Jan. 23, 1952 3 Sheets-Sheet 2 .617 non J? b 47 i fkaMSauRGE P/crURE 1 VENTOR. MW

. A TT ORNE Y Oct. 17, 1939. L.-A. GOULD TELEVISION APPARATUS AND METHODFiled Jan. 23, 1932 3 Sheets-Sheet 3 I VENTOR.

TTORNEY Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE Leslie A.Gould, Bridgeport, Conn, assignor to Radio Inventions, Inc., New York,N. Y., a corporation of New York Application January 23,

2 Claims.

The present invention relates to a method and apparatus for scanning anoptical image, as in television reception or transmission or the like.One object of my invention is to secure an image of greater brilliancethan has been heretofore commonly obtained by the use of a gas glowtube.

Another object of my invention is to secure alarge image in relation tothe size of the apli); paratus used.

A further object of my invention is to secure a scanning mechanism whichrequires only a low degree of accuracy for its manufacturing, and isconsequently inexpensive to make.

A still further object of my invention is to secure a form of glow tubeand method of operating the same, capable of very faithful modulationand consuming a relatively small amount of power in the glow tube.

,Another object of my invention is to secure a scanning apparatus bywhich the image may be viewed directly or may be projected upon a screenat will. v r

. My invention attains the above objects by uti- 25 lizing a novelcombination of a glow tube disposed in a helical configuration andlocated within a rotatable cylinder or drum, the drum for example beingpunctured with a series of regularly spaced apertures arranged injuxtaposition to 30 the helical glow tube within, and includes suitableelectrical circuits for supporting a picture signal to the glow tube.

Several forms of apparatus of my invention may be more easily understoodby reference to the drawings forming part of this specification.

Fig. 1 is a view in elevation, representing the mechanical and opticalportions ofone form of the apparatus of my invention.

Fig. 2 shows in plan view a detail of a part :40 of Fig. 1, namely thecommutator for connecting in the proper order the picture signal to eachturn of a two-turn glow tube.

Fig. 3 is a schematic diagram illustrating one form of electricalcircuits for generating a pic- ;45 ture-modulated high-frequency currentto be delivered to the glow tube.

Fig. 4 is a plan view of a commutator for connecting in the proper orderthe picture signal to each convolution of a three-turn glow tube.

Figs. 5 and 6 illustratealternative forms of my invention utilizingselective screening, instead of selective illumination.

Referring now to Fig. 1, a drum II is shown, constructed preferably ofBakelite or other insu- 35g lating material having considerablemechanical 1932, Serial No. 588,333

strength, reinforced by metal band I2 and mounted in flanged floor plateI3. This floor plate may be arranged to be rotated by a motor 2I(preferably of the synchronous type) through motor shaft 20, gear I9fixed thereon, engaging gear I8 fixed upon shaft I5 which is supportedin bearings I 6 and I1, and carries floor plate I3 mounted thereupon bymeans of flanged collar I4.

To the inner surface of drum I I is fixed by means of clamps 23 or othersuitable means a helical glow tube 22 made of glass tubing or othersuitable transparent insulating medium bent to shape, provided with aplurality of suitable electrodes spaced approximately 360 apart alongits length, and enclosing a gaseous medium capable of a glow dischargeunder electrical excitation, such as neon, helium, mercury vapor or thelike. Any mechanical unbalance of the system when rotating may becorrected by means of small weights II secured to drum II at properpoints to correct for any unsymmetrical placement of tube 22 giving riseto kinetic unbalance of the rotating system.

A plurality of substantially equally spaced apertures 24 (preferably ofrectangular shape and having bevelled edges) are disposed in the form ofa helix about the drum I I and coordinate with glow tube 22 to allow theemergence of its light therethrough.

The action of the helix of apertures is to scan the image beingreproduced, so that an observer viewing the drum I I will see aplurality of images spacedadjacent to one another about said drum.Aframing stop 25 with a suitable opening 26 may be placed close to thedrum to limit the view tpo 'a single complete image, or severalobservers may view different substantially complete images at differentpositions.

As hereinafter shown and described, the helical tube itself may serve tovertically delimit a single elemental area, so that vertical slits maybe cut in the drum, instead of apertures 24.

, Motor 2I may conveniently have its phase relationship and angle ofmechanical lag controlledby switch I0 and rheostat II, although othersuitable means may be employed for this purpose.

In one form of the apparatus of my invention here described, a helix oftwo complete turns (720) is used, but a greater number of turns or asingle turn may be used. The size of the area scanned is obviouslyincreased by increasing the number of turns, other factors remainingequal.

Referring now to Figs. 1 and 2, the picture signal carrying conductorsmay be connected to each turn of glow tube 22 in succession by means ofany suitable commutator system of which one form is here illustrated.The central electrode of this glow tube may be grounded conductively tofloor plate l3 by means of lead 2'! and lug 28.

A high tension lead 29 conducts current from the source of the picturesignal to a stationary brush 3% which is supported in an insulatingbrush holder 3! and bears upon slip ring 32, the slip ring acting as theexternal portion of the commutator S3. The inner surface of thecommutator is provided with a 180 insulating segment at of fibre orsimilar material and a 180 conducting segment 35 which is integral withthe body of the commutator. Commutator 33 is concentric with shaft l5and revolves in the same direction as, and at one-half the angular speedof the shaft. Shaft i5 is provided with a longitudinal central channel36 for carrying distribution leads 3i and 33 from the commutator location to the electrodes of the glow tube. Two insulating brush holders 39and Mare spaced 180 apart and fixed to shaft l5, their brushes 4| and &2bearing upon the inner surface of commutator and being connected todistribution leads 3'! and 38. Ihus when the apparatus is in operation,the conductors carrying the picture signal are connected alternately toeach turn of the helical glow tube, and remainin contact with eachduring one revolution of shaft [5.

If the source of picture signal delivers a modulated high-frequencycurrent, stationary brush may be replaced by a stationary capacityeleslip ring 32, current transfer being then effected through the agencyof the capacity existing between the conducting plate and said slipring, or

. other methods of energy transfer, such as induction or radiation maybe employed for this purpose.

Referring again to Fig. 1 certain possible methods of mounting and ofrotating commutator 33 are illustrated. This commutator maybe supportedby an insulating ring 43 which is in turn supported upon gear 64rotatably mounted on shaftlii by means of bearing 45. Gear 46 engages agear 36 fixed to motor shaftZlI, theratio of these gears beingcalculated from the rotational speed requirements given above.

Referring to Fig. 3, a thermionic vacuum tube is there shown as arrangedto produce sustained high frequency oscillations through the agency ofreactors i8 and 49 in its grid and plate circuits, respectively, thesereactors being mutually coupled with one another. Glow tube 22 with itsassociated commutator 33 may be positioned in series with the platereactor 49 and with a capacitor 59, all these reactors and capacitorsbeing chosen of such values as to possess substantially equal reactancesto currents of the frequency generated, so as to compose a seriesresonant circuits A variable capacitor 5! may be bridged acrosscapacitor 58 and glow tube 22 for the purpose of independentlyincreasing the current through reactor 49, thus increasing the amplitudeof oscillation. The addition of this variable capacitor 5! may makenecessary a different value of series capacitor 50.

Oscillating tube ll may be arranged to be modulated by a picture signal(as from a receiver) through the thermionic tube 52 acting as anampiifier and modulator by the agency of a reactor 53 inits platecircuit. The modulating voltage appears across reactor 53 and may beconducted to the plate circuit of oscillator tube il through reactor 55,according to the familiar Heising system with parallel feed. Thefilaments or cathodes of tubes ll and 52 may be heated by current fromany suitable source as from a transformer 55, the electrical center ofsaid source being conductively connected to the proper circuits of saidtubes. Batteries 56, 5'? and 58 or other sources of substantiallycontinuous current may supply the proper potential to certain of thecircuits of said thermionic tubes employing suchcontinuous current.

Fig. 4 shows one form of commutator which can be used with a spiral gastube of three turns, In this figure a 128 insulating segment 65 isshown, interposed between a conducting segment 66 which is insulatedfrom the body 35 of the commutator as by an appropriate sheet 66 ofinsulation and .is connected (grounded) to shaft l5, and a 120conducting segment 61 forming an integral part of the commutator body33'. The external face of commutator body 33 is formed into a slip ring32. Three equally spaced brushes 68 bear upon the commutator and resupported on shaft i5 by insulating brush holders 69.

A three-turn helical glow tube (not shown) would have the electrodes atits ends connected together as one terminal and a single lead broughtdown from this connection to a brush 58 (Fig. 4) The two intermediateelectrodes are each connected through a lead to one of the other twobrushes 68, in the proper sequence.

The voltage applied may be so adjusted that it is sufficient to. breakdown a single turn of glow tube 22 to which it is applied, but. willnotbreak down the other two turns which are-effectively in series. Thecommutator shouid revolve in the same direction as the scanning drum,and at the rotational speed of the latter;

Helical glow tubes of any number of turns may be operated similarly, thenumber of brushes and of, commutator segmentseach being equal to thenumber of turns in the helix. Two adjacent comso, i

mutator segments should be conducting, and

the remainder insulating as in the case of a' three-turn helix. Theratio of the rotational speed of the commutator to the rotational speedof the scanning drum should be where N is the number of'turns in thehelical glow tube, and the rotational direction of the commutator shouldbe thejsame as that of the In the operation of small sized apparatusaccording to this invention I have observed that thermionic tubes'dl'and 52 may be of 7 watt rating or smailer and yet be very successful inoperation and that a high-frequency current of i0 milliamperes throughglow tube 22 is usually sufficient to produce a comparatively brilliantillumination. Since this glow tube is in close pro-ximity to apertures 23 its light is effectively utilized, i. e., is directlyavailable forviewing from in the tube, modulated with the picture signal. However, Ihave also operated the glow tube di rectly from the picture signal, itbeing usually preferable to provide a component of continuous currentthrough the glow tube for the latter system.

Drum I i may be of metal when using this latter system, but when usingthe high frequency system certain capacity effects such as that from theglow tube to the drum may make such metallic construction inadvisable.

The image may be viewed by any one of three methods, namely, (1) viewingthe image at the drum directly or through a magnifying lens, (2)projecting the image from the drum to an opaque screen by means of alens, or (3) projecting the image from the drum to a translucent screen.These methods may be used interchangeably, as will be described below.

Assuming that the image is to be scanned from left to right andprogressively downward, and is to be viewed directly at the drum, thedirection of winding of the helical glow tube and the direction ofrotation of the drum should be as shown in Fig. 1.

As the drum revolves, the upper turn of glow tube 22 being lighted, eachaperture 24 moves across the field of view and produces one line of theimage, successive lines being displaced downward by the widthof oneline. When drum I I has completed one revolution the lowest aperture 24in the upper turn of glow tube 22 has passed across the field of view.Commutation now occurs and the lower turn of the glow tube is lighted,scanning continuing downward. When drum I! has completed the secondrevolution, commuta tion again occurs and the upper turn of the glowtube is lighted. This cycle is repeated at a rate greater than thepersistence of vision and an image having apparent motion may be seenthrough viewing aperture 28.

A magnifying lens t t may be placed before the drum to enlarge theapparent size of the image without reversing the horizontal or verticalrelation of the image to an observer.

If, however, the'image is to be projected upon a translucent screenthrough a focusing lens it becomes necessary to re-invert it (since thefocusing lens acts to invert it) which may be accomplished by properlyplacing two inclined mirrors (or a. single prism) in the optical pathbetween the drum and screen and properly placing the screen. Theenlarged image will then be viewed from the side of the translucentscreen opposite the focusing lens, and will appear in the properhorizontal and vertical relation.

If the image is to be projected upon an opaque screen through thefocusing lens it becomes necessary to re-invert the image (afterinversion by the lens) and to reverse it in the right and leftdirection, which may be accomplished by two pairs or" inclined mirrors,inclined upon axes at right angles to one another. Likewise two prismsmay-be used, as is familiar in the construction of certain field oropera glasses.

In case it is desired only to view the image at the drum. (through amagnifying lens), the glow tube 22 may be constructed with a pitchrelative- 1y greater in the ratio that the image is to be magnified, anda cylindrical magnifying lens used in place of lens 64%, with its axisparallel to the axis of drum II. It may be an advantage to in-- creasethe pitch of helical glow tube 22 for the sake of ease in constructionand then magnify in one dimension only.

It is understood that any desired size and ratio of the component partsof the apparatus of my invention may be used without departing from thefield of my broad invention, but the following example will illustratea, possible construction.

For receiving a visual image scanned with 60 lines at 20 pictures persecond, scanning being from left to right and progressively downward,the helical glow tube 22 of Fig. 1 may be wound as in a right handscrew, and the drum II revolved so that the side nearer an observermoves from left to right. There should be 60 apertures 2 3 and theseapertures should be spaced 12 angular degrees apart around the drum. Thepitch of the helical glow tube 22 may be such that the axial distancefrom the uppermost aperture in the helix to the lowest aperture in thehelix is somewhat less than the peripheral distance between any twoadjacent apertures, according to the ratio or" image height to widthdesired. The rotational speed of drum H should be 2400 R. P. M., and therotational speed of commutator 33 should be 1200 R. P. M., a speed ratioof 2:1. Framing of the image in viewing aperture 26 may be eiiected bymeans of a switch ill and variable resistor ii, in the motor supplyline. When the apparatus is operating, varying the resistor 'lI causesthe image to move horizontally, and momentarily opening switch 1!]causes the image to move vertically. Proper manipulation centers theimage in aperture 26.

, Another framing method, such as producing plurality of images andmoving a selective framing aperture, may be employed, as well as othersuitable methods familiar in the art.

If a single-turn helical glow tube 22 is used, no commutation isnecessary, and a single slip ring may be mounted upon shaft I5 forconducting the picture signal to the glow tube.

The drum Il may be eliminated if desired, and the helical glow tube 22mounted in other supporting means. The glow tube may then be coated withan opaque layer of black enamel or other suitable material, in whichproperly spaced light apertures are produced, as by grinding, scrapingor otherwise removing the enamel.

In Fig. 5, motor IUI, on support I02, rotates drum I03, containinghelical gas tube I04, receiving current through electrodes at each endthereof. One end may conveniently be grounded to the metal frame workwhich may be connected to the low-potential terminal of the signalsupply by lead I05 while the other end may be connected to slip ringI06, upon which bears brush it, connected by lead I08 to thehigh-potential terminal of the signal supply.

Drum I03 may be provided with slits I09 or the perforations of thepreviously described forms may be employed. Without drum I03 andconcentric therewith, rotates drum H0, driven by gear Ill. Idler gearII2 fixed to idler gear H3, both rotatable upon fixed shaft I I6 anddriven by gear H4 upon the motor shaft, rotates drum H0 at a speed lessthan that of drum I63, in this case at one third the speed.

Drum I I0 is provided with horizontally disposed slots H5 which may beequal in number to the number of convolutions of tube I04, which serveto allow the viewing of only a single turn of tube I04 at any oneinstant.

By this construction the use of selective illumination of portions ofthe gas tube is avoided, and selective screening of the illumination ofthe totality thereof is employed to replace the same.

In Fig. 6, the motor, the spiral gas tube and its drum, and the mode ofcurrent conduction thereunto may be similar tothe corresponding parts inFig. 5. Apertures 289 are shown in this form, but slits like those ofFig. 5 may be used without other change. 7

A second scanning drum 2H] is driven by sprocket 21 I, deriving itsmotive power through bevel gear 2!? from the motor Zlll by means ofshaft 2|6, bevel gears 2H and H8, and shaft 2l9. Drum 2H1 rotates at aspeed S which is preferably an integral fraction of the motor speed andsuch that speed S in revolutions per second equals the number ofpictures per second divided by the number of slits 2|5.

Slits M5 on drum 2H] are moved at right angles to the spiral tube drum293, and fulfill substantially the same screening functions as the slitsI I5 of Fig. 5. Mirror 23L supported within drum 2!!) by means ofbracket 230 at approximately 45", may serve to project the scanned lightrays without the drum and in a direction substantially parallel with theaxis thereof. V

The forms of Figs. 5 and 6 may be subjected to the same modifications asthose of the first described form of my invention, such as would beapparent to those skilled in the art.

For example, the screening slits may be located upon a disc or beltinstead of the drums here 30 shown.

By suitable substitutions familiar to one skilled in the art, such asthe substitution of a helical light sensitive cell for the glow tube, myinvention may be used for transmission scanning.

It is understood that the apparatus of my invention may be subject tomany other changes, as 5 will be obvious to one skilled in the art,without exceeding the scope of my broad invention which is limited onlyby the appended claims.

I claim:

1. Television scanning apparatus including a 1 helical glow tube havingall its turns of equal radii rotating about its axis, a screening memberrotating therewith and exposing a plurality of elemental areas ofdiscrete turns of said tube at one instant, and a separate screeningmember 1 rotating in synchronous relationship with the first mentionedscreening member and screening all but one of said elemental areas atany one instant.

2. A television scanner including two drums provided with suitable slitsupon their peripheries 2 and rotating at right angles to each other, oneof said drums enclosing and rotating therewith light producing meansresponsive to television signals and disposed in helical forms, saidrotation of the helical light producing means cooperating with 2 therotation of the enclosing drum thereof to scan an opticalimage at aplurality of points simultaneously, and the other drum cooperating byits rotation so that only one of said plurality of scanning points shallbe visible at one instant.

LESLIE -A. GOULD.

